PATCH: [[ -v varname ]]

[Oliver Kiddle <okiddle@xxxxxxxxxxx>]

On 9 Sep, Stephane Chazelas wrote:
> You guys may want to comment on the latest proposal there:
> http://austingroupbugs.net/file_download.php?file_id=31&type=bug
> as it would make zsh non-conformant.

One thing it also includes is the bash/ksh [[ -v ... ]] condition for
checking if a particular variable is set. Zsh has the ${+varname} syntax
which provides the same functionality in a different form. The following
patch adds the ksh form for compatibility.

The code for ${+...} is mixed in with the rest of the parameter
substitution code so I couldn't easily reuse it. There may be subtle
differences as a result. In particular it returns false for a string
slice. That's arguably not a variable and would raise the question
of string slices on an array slice.

There's also subtle differences relative to bash/ksh. local/typeset
in bash/ksh leave the variable undefined until it is given a value
rather than making it an empty scalar. And bash doesn't seem to handle
the positional parameters.

Oliver

diff --git a/Completion/Zsh/Context/_condition b/Completion/Zsh/Context/_condition
index 6f5e601..0285911 100644
--- a/Completion/Zsh/Context/_condition
+++ b/Completion/Zsh/Context/_condition
@@ -8,6 +8,8 @@ elif [[ "$prev" = -([a-hkprsuwxLOGSN]|[no]t|ef) ]]; then
   _tags -C "$prev" files && _files
 elif [[ "$prev" = -t ]]; then
   _file_descriptors
+elif [[ "$prev" = -v ]]; then
+  _parameters -r "\= \t\n\[\-"
 else
   if [[ "$PREFIX" = -* ]] ||
      ! zstyle -T ":completion:${curcontext}:options" prefix-needed; then
@@ -30,6 +32,7 @@ else
 	           -s:non-empty\ file
 	           -t:terminal\ file\ descriptor
 	           -u:setuid\ bit
+		   -v:set\ variable
 	           -w:writable\ file
 	           -x:executable\ file
 	           -z:empty\ string
diff --git a/Doc/Zsh/cond.yo b/Doc/Zsh/cond.yo
index 474baa1..e08fc0d 100644
--- a/Doc/Zsh/cond.yo
+++ b/Doc/Zsh/cond.yo
@@ -63,6 +63,9 @@ is open and associated with a terminal device.
 item(tt(-u) var(file))(
 true if var(file) exists and has its setuid bit set.
 )
+item(tt(-v) var(varname))(
+true if shell variable var(varname) is set.
+)
 item(tt(-w) var(file))(
 true if var(file) exists and is writable by current process.
 )
diff --git a/Src/cond.c b/Src/cond.c
index f25ebd4..42e9de3 100644
--- a/Src/cond.c
+++ b/Src/cond.c
@@ -351,6 +351,8 @@ evalcond(Estate state, char *fromtest)
 	return (!S_ISSOCK(dostat(left)));
     case 'u':
 	return (!(dostat(left) & S_ISUID));
+    case 'v':
+	return (!issetvar(left));
     case 'w':
 	return (!doaccess(left, W_OK));
     case 'x':
diff --git a/Src/params.c b/Src/params.c
index 842b2f0..5c534af 100644
--- a/Src/params.c
+++ b/Src/params.c
@@ -626,6 +626,36 @@ getvaluearr(Value v)
 	return NULL;
 }
 
+/* Return whether the variable is set         *
+ * checks that array slices are within range  *
+ * used for [[ -v ... ]] condition test       */
+
+/**/
+int
+issetvar(char *name)
+{
+    struct value vbuf;
+    Value v;
+    int slice;
+    char **arr;
+
+    if (!(v = getvalue(&vbuf, &name, 1)) || *name)
+	return 0; /* no value or more chars after the variable name */
+    if (v->isarr & ~SCANPM_ARRONLY)
+	return v->end > 1; /* for extracted elements, end gives us a count */
+
+    slice = v->start != 0 || v->end != -1;
+    if (PM_TYPE(v->pm->node.flags) != PM_ARRAY || !slice)
+	return !slice && !(v->pm->node.flags & PM_UNSET);
+
+    if (!v->end) /* empty array slice */
+	return 0;
+    /* get the array and check end is within range */
+    if (!(arr = getvaluearr(v)))
+	return 0;
+    return arrlen_ge(arr, v->end < 0 ? - v->end : v->end);
+}
+
 /*
  * Split environment string into (name, value) pair.
  * this is used to avoid in-place editing of environment table
diff --git a/Src/parse.c b/Src/parse.c
index 6e7d40e..2f81939 100644
--- a/Src/parse.c
+++ b/Src/parse.c
@@ -2386,7 +2386,7 @@ par_cond_2(void)
     s1 = tokstr;
     dble = (s1 && *s1 == '-'
 	    && (!n_testargs
-		|| strspn(s1+1, "abcdefghknoprstuwxzLONGS") == 1)
+		|| strspn(s1+1, "abcdefghknoprstuvwxzLONGS") == 1)
 	    && !s1[2]);
     if (tok != STRING) {
 	/* Check first argument for [[ STRING ]] re-interpretation */
@@ -2465,7 +2465,7 @@ par_cond_double(char *a, char *b)
 {
     if (a[0] != '-' || !a[1])
 	COND_ERROR("parse error: condition expected: %s", a);
-    else if (!a[2] && strspn(a+1, "abcdefgknoprstuwxzhLONGS") == 1) {
+    else if (!a[2] && strspn(a+1, "abcdefgknoprstuvwxzhLONGS") == 1) {
 	ecadd(WCB_COND(a[1], 0));
 	ecstr(b);
     } else {
diff --git a/Test/C02cond.ztst b/Test/C02cond.ztst
index 78e644a..40e4dfb 100644
--- a/Test/C02cond.ztst
+++ b/Test/C02cond.ztst
@@ -269,6 +269,25 @@ F:Failures in these cases do not indicate a problem in the shell.
 0:-nt shouldn't abort on non-existent files
 >status = 1
 
+  str='string' empty=''
+  [[ -v IFS && -v str && -v empty && ! -v str[3] && ! -v not_a_variable ]]
+0:-v cond
+
+  arr=( 1 2 3 4 ) empty=()
+  [[ -v arr && -v arr[1,4] && -v arr[1] && -v arr[4] && -v arr[-4] &&
+    -v arr[(i)3] && ! -v arr[(i)x] &&
+    ! -v arr[0] && ! -v arr[5] && ! -v arr[-5] && ! -v arr[2][1] &&
+    ! -v arr[3]extra && -v empty && ! -v empty[1] ]]
+0:-v cond with array
+
+  typeset -A assoc=( key val num 4 )
+  [[ -v assoc && -v assoc[key] && -v assoc[(i)*] && -v assoc[(I)*] &&
+    ! -v assoc[x] && ! -v assoc[key][1] ]]
+0:-v cond with association
+
+  () { [[ -v 0 && -v 1 && -v 2 && ! -v 3 ]] } arg ''
+0:-v cond with positional parameters
+
 # core dumps on failure
   if zmodload zsh/regex 2>/dev/null; then
      echo >regex_test.sh 'if [[ $# = 1 ]]; then